Best Silo Storage Applies for a Business Loan from County

Best Silo Storage applies for a business loan from County Credit Union.To help Best Silo get the loan so that it will be able to stay in business and fulfill a deal it has made with her,Dakota promises the credit union's loan officer that she will repay the loan if Best Silo does not.To be enforceable,Dakota's promise

A) need not be in writing.
B) must be in writing because it benefits Best Silo.
C) must be in writing because the credit union is not a party to the other deal.
D) must be in writing because it benefits Dakota.